DE 29 50 660--A proposes a brake caliper having cast in reinforcement parts made of a higher strength material which may be steel, hard metal or ceramic.
JP 59-123997--A provides a rocker arm made as an aluminium alloy casting with a sintered body of porous ceramics disposed in the pad position of the rocker arm, and made by locating the sintered body into the mould and filling the mould with molten alloy under high pressure and maintaining the pressure until the alloy solidifies.
The designer of a brake caliper is particularly concerned to provide stiffness, so that when the brake pads are forced against the disc the caliper will not deform under load and hence reduce or vary the pad pressure distribution. The problem in providing adequate stiffness is due to the overall limitations of space availability especially when the caliper is within a wheel, as well as the restrictions of available materials on inherent stiffness, cost and weight limitations.
For high duty purposes, for example racing car brakes, the caliper is usually made of an aluminium alloy or a so-called composite material in which particles or fibres of silicon carbide or the like are distributed uniformly through the metal: this composite-material does indeed have an improved modulus of elasticity but is extremely difficult to machine because the silicon carbide is not only stiffer but is extremely hard and tends to damage cutting tools. The cutting rates, lubricant requirements and so forth for the aluminium matrix and ones which might suit the silicon carbide are widely different.
The object of the invention is to provide improved stiffness whilst enabling the necessary machining to be carried out.